Faster change-over times in the inking unit with anilox rollers!
In the printing process the printing ink has to be forwarded to the ink unit in measured out quantity. A simple to reproduce quantity can be defined by so-called laser engraved rollers (German) or "anilox" rollers (English, following the anilin ink system).
 An anilox roller is a hard cylinder, usually constructed of a steel or aluminium core which is coated by an industrial ceramic whose surface contains millions of very fine dimples (cells). Depending on the design of the printing unit version, the anilox roller is either semi-submersed in the ink fountain, or comes into contact with a so-called "metering roller" which is semi-submersed in the ink fountain. In either instance, a thick layer of typically low viscous ink  is deposited on the roller. A razor-sharp 'ductor blade' is used to scrape excess ink from the surface leaving just the measured amount of ink in the cells. The roller then rotates to contact either a further transfer roller (offset printing) or a cliche plate (flexo printing). These then receive the ink from the cells for transfer to the printed material. As there does not exist any ink zones, these ink units does not need an axial distribution (oscillation).
 Grauel uses anilox rollers for both it's flexographic printing units as it's dry-offset printing units. The main advantage for applying anilox rollers is the lower viscose ink (which especially for the surface pressure tend to has a steady, even flow) in combination with the fixed ink volume that is transfered into the printing process per circumference of the roller. The ink volume is defined in cm3/m2. This amount corresponds to a layer thickness of 0,001 mm (1µ) with an average special ink weight of 1g/cm3. Of course, onto the substrate only appears the ink quantity less the transferring losses per splitting process (average value approx. 50 %) between the rollers. These simplified assumptions are only subject to a better understanding of the whole context.
The usage of anilox rollers results in a high process stability and no need for adjustments of the ductor blade settings by the operator.
Cleaning the Anilox rollers
During operation, the cells can get contaminated with ink  residue that decreases the ink volume. For daily maintenance, the rollers should therefore be cleaned with a special cleaning agent (article TR03 no. 88201003) that retrieves (ink)-residue in the cells without damaging it's structure.
To restore the anilox roller back to it's original ink volume, Grauel offers it's customer to clean the rollers using bi-carbonate powder. This cleaning method is cost friendly and has no risk of damaging the ceramic layer. For more information please contact us.
Contact:
Printing heads & Machines:
Grauel International bv
Grasbeemd 2
5705 DG Helmond - Netherlands
T: +31 492 565 010
I: www.grauel.nl
E: grauel@grauel.nl
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Improved coating
 Recently, Grauel improved the coating for the ink transfer rollers. The function of these rollers is to work the thick offset ink into an even and smooth ink layer in axial direction. Therefore: the harder and smoother the surface of the roller, the better the print!
Thereby the used materials play a not to undervalue role for an optimum ratio between ink trapping- and ink lay-down characteristics. For more information, just call customer service: +49 3034 99370.
A closer look!
The picture on the left is a close up of a typical 5 ml syringe, printed on a Grauel UV offset printer.
Underneath, you can see the same syringe but then 1000 times magnified! The shot was taken with a keyence VHX-600 digital microscope. With this device we are able to interpret the substrate, layer thickness, surface and distribution in much more detail.
As you can see here very well, the high tack of the ink gives the print a more or less strong "troubled" image during the splitting process . This effect is intensified with increasing print velocity and has to be compensated with more pressure of the offset roller.
Axial cliché adjustment, faster changes
Especially for one colour printheads, Grauel recently developed a simple tool for axial cliché adjustment. By turning an adjusting nut with scale on the cliché cylinder,  the cliché can move within a window of approx. 3 mm. Ideal for fast restoring of print subjects or simple readjusting of the side lay register of 0-lines for all kinds of scales. The exact position is indicated, and therefore repetitive. For more information please call +31 492 565 010.
Upcoming Shows
MEDTEC 2008: 11 - 13 March, Messe Stuttgart
FAKUMA 2008: 14 - 18 October, Friedrichshafen
Contact:
Spare parts, Clichés & Inks:
B. Grauel GmbH
Reuchlinstrasse 10-11
10553 Berlin - Deutschland
T: +49 30 34 99 370
I: www.grauel.de
E: grauel@grauel.de
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